Count All Palindromic Subsequence in a given String | C # code to Count Palindromic Subsequence Subsequence in a given String ; Function return the total palindromic subsequence ; create a 2D array to store the count of palindromic subsequence ; palindromic subsequence of length 1 ; check subsequence of length L is palindrome or not ; return total palindromic subsequence ; Driver Code
using System ; class GFG { static int countPS ( string str ) { int N = str . Length ; int [ , ] cps = new int [ N + 1 , N + 1 ] ; for ( int i = 0 ; i < N ; i ++ ) cps [ i , i ] = 1 ; for ( int L = 2 ; L <= N ; L ++ ) { for ( int i = 0 ; i <= N - L ; i ++ ) { int k = L + i - 1 ; if ( k < N ) { if ( str [ i ] == str [ k ] ) cps [ i , k ] = cps [ i , k - 1 ] + cps [ i + 1 , k ] + 1 ; else cps [ i , k ] = cps [ i , k - 1 ] + cps [ i + 1 , k ] - cps [ i + 1 , k - 1 ] ; } } } return cps [ 0 , N - 1 ] ; } public static void Main ( ) { string str = " abcb " ; Console . Write ( " Total ▁ palindromic ▁ " + " subsequence ▁ are ▁ : ▁ " + countPS ( str ) ) ; } }